The present invention relates to clamp systems for joining the ends of tubes to surfaces, and in particular to clamp systems for joining the ends of a high temperature fluid bearing tube, such as an exhaust gas recirculation (EGR) tube, to an intake manifold or EGR valve of an internal combustion engine.
A modern automobile internal combustion motor requires or is provided with a variety of co-operative apparatuses which involve the use of tubes to transmit pressurized fluid (such as exhaust) or provide a vacuum, to a portion of the motor block, throttle body, intake or exhaust manifolds, or other components. For an example, an exhaust gas recirculation (EGR) tube directs hot exhaust gases from the exhaust manifold or another part of the exhaust system, to the throttle body or air intake manifold, which improves the quality of the vehicle's exhaust emissions and can improve fuel efficiency. In the environment of an EGR tube, in particular the end of the EGR tube which is affixed to the "hot end" (the exhaust manifold or similar source), the temperatures of the gases may well reach significantly above 1,000 degrees Fahrenheit.
Typically, an accessory tube will be insertingly received at its ends directly into apertures provided in the side walls of the respective motor components. Each end of the tube may be provided with an outwardly-extending, annular bead, to, in part, limit the extent to which the tube extends into the side wall of the motor component, and as well to provide a surface for a clamp to hold the tube end in place, and to provide a seal to prevent the escape of the gases or other fluids in the tube to the surrounding environment.
A typical prior art clamp used to secure such a tube end may be fabricated as a simple plate-like bracket member, with a tube aperture and one or more bolt apertures. The side of the bracket member, which would face the surface of the component to which the tube end is being clamped, would press the bead or flange projecting radially outward from the tube between the bracket member and the component surface. Typically, the flange may consist of either a solid or hollow radial projection, which might be either directly formed from the material of the tube, such as by drawing and compressing a fold of the tube outwardly to form the flange, or by affixing, such as by welding or brazing, a separate member onto the tube to form the flange. In addition, the flange typically would have a substantially uniform thickness along its radial width, such that the flange has a relatively wide annular area of surface contact with both the bracket member and the surface.
It is possible to provide gaskets which facilitate the creation of an effective fluid-tight seal for such embodiments. Such gaskets are capable of withstanding, for at least economically effective periods of time, the high temperatures and thermal cycling associated with such environments. It is desirable, however, to obtain a maximum possible lifespan for all the involved components, in order to lengthen the periods between necessary inspections and subsequent replacement operations, so as to reduce maintenance costs and efforts. It is known that the heat of the fluid passing through the tube can migrate radially through the flange and expose the gasket and mating surfaces of the housing and bracket member to additional and higher temperatures than those encountered directly through the surface of the component against which the gasket is positioned.
Accordingly, it is desirable to provide a clamp system having a construction which reduces the transfer of heat radially from the high-temperature fluid bearing tube, so as to further protect the seal and mating surfaces and extend the functioning lifespan of those components subject to heat degradation.
An additional consideration is the drive to continually reduce the cost of the component parts in an internal combustion engine. For example, substantial cost savings can be achieved by fabricating the intake manifold and/or throttle body from aluminum. However, continued direct exposure of aluminum to recirculated exhaust gases and the heat such gases contain is potentially damaging to components made from aluminum.
Accordingly, it is an additional object of the invention, to provide a clamp system, for use in an exhaust gas recirculation system, which enables the use of lower cost materials, such as aluminum, in the construction of the components receiving the recirculated gases, such as intake manifolds and throttle bodies.
A typical construction of such prior art clamp systems involves affixing the tube end to the bracket member, by welding or brazing, which can be a time consuming and costly process, considering the relatively small size and other costs of the component.
It is accordingly still another object of the present invention to provide a clamp system for clamping an end of a tube to a component housing, in which the tube end is fixedly held by a bracket member without the use of welding or brazing.
These and other objects of the invention will become apparent in light of the present Specification, Claims and Drawings.